Conventionally, electronic equipment such as a personal computer and an entertainment device may include a main unit (a main body of the electronic equipment) and an external unit connected and placed adjacent to the main unit such as, for instance, external equipment for enhancing functions of the main body of the electronic equipment.
In recent years, the external unit described above tends to be smaller in size and higher in density, and heat generated inside the external unit is hardly discharged to the outside. To cool the heat, it is conceivable to apply a cooling mechanism such as a fan or a heat sink to the external unit, but when these types of mechanisms are applied, further size reduction of the external unit becomes difficult.
An object of the present invention is to provide a cooling system for cooling an external unit connected and placed adjacent to a main unit, especially a cooling system enabling cooling without impeding size reduction of the external unit, and also to provide an external unit and electronic equipment used for the cooling system as described above.